Process and device for the manufacture of fleeces of mineral fibers



March 9, 1965 R. SALTERI ETAL 3,172,184

PROCESS AND DEVICE FOR THE MANUFACTURE OF FLEECES OF MINERAL FIBERSFiled June 19, 1961 K A4-c S y/+221.

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United States Patent 3,172,184 PROCESS AND DEVICE FOR THE MANUFACTURE OFFLEECES 6F MINERAL FIBERS Renato Saiteri, Milan, and Erich Hesselbarth,Barlassina, Milan, Italy, assignors to Vitrofil S.p.A., Milan, Italy, acompany of Italy Filed June 19, 1961, Ser. No. 118,090 Claims priority,application Italy, June 25, 1960, "636,174 6 Claims. (Cl. 28-1) It is anobject of the present invention to provide a process and device formanufacturing fleeces of mineral fibers, in particular of glass fibers,which have a high tenacity per unit weight, as well as fleeces obtainedby said process and device.

The term fleeces is used herein to designate continuous webs havinglayers of filaments arranged partly longitudinally and partlynon-longitudinally with respect to the axis of the web, wherein thefilaments may be continuous or discontinuous, and are fixed with respectto one another by means of suitable adhesive.

Such webs, which are known in the art as fleeces (German Vlies), differfrom common felts obtained from short fibers arranged at random.

There are several known processes and devices for obtaining fleeces offibers, wherein the direction of the fibers is more or less at randomand the fibers are generally discontinuous, and are of greater orsmaller length. So, for instance, it is possible to extrude glassfilaments from convenient spinnerets, to break off these filaments bymeans of a stream of hot gas, and to deposit upon a net or gauze orother device the short fibers so obtained. Or it is possible to produceglass filaments by spinning from a rod, namely by melting a certainnumber of glass rods at their ends, advancing these filaments on a drumor similar device, and then detaching them from the drum surface anddepositing them on a tape, whereby said filaments become broken and lieon the tape at random.

There is no way in practice of controlling the orientation of the glassfibers, nor of arranging them in any determined desired way.

The present invention provides a process and device for manufacturingfleeces, to obtain different orientation of the filaments whilecontrolling said orientations. It permits moreover obtaining a fleececomprising continuous filaments or discontinuous filaments but ofconsiderable length. In any case, the strength of the fleece obtained isfar higher than that of any fleeces known heretofore. As for theinvention, it is of no consequence how the filament-s are produced orformed, but commonly they are produced or formed just by spinning fromrods. However the mention of a spinning method should not be construedas a limitation of the scope of the patent by any means.

The process according to the invention comprises advancing parallelglass filaments, howsoever produced, over a portion of a cylindricalsurface, then disengaging them from that surface, and advancing themwhile causing them to converge, and then projecting them by effect of astream of air in periodically variable directions upon 7 a support wherethey become arranged in mutually crossing directions and mutuallyintermesh to constitute the fleece, and whence they are finally removedcontinuously in the shape of a fleece. Preferably the filaments aresubdivided into two groups, one of which is arranged in a substantiallylongitudinal direction with respect to the axis of the fleece to beobtained, while the other one is placed in zigzag fashion with respectto said axis. In that way, the first group of filaments impartsconsiderable strength to the fleece in the longitudinal direction,

3,172,184 Patented Mar. 9, 1965 while the filaments arranged in zigzagor transverse fashion, impart considerable transverse strength thereto.

The device according to the invention comprises a rotary drum oranalogous element which receives and advances glass fibers generated byany convenient means, a shell enveloping a portion of said drum anddefining therewith a narrow space through which said filaments travel,the rotation of the drum in juxtaposition to said shell generating astream of air, an element that separates the filaments from said drum, afixed conduit having a tapering cross-section to receive the filamentsseparated from the drum and adapted to cause the filaments to convergeas they advance in this conduit, a pivotal conduit having a pendularmovement andan open outlet, to direct the filaments in ditferentdirections, a tubular element arranged transversely and interposed inthe path of the filaments issuing from the pivotal conduit to engagepart of the filaments, a netlike stationary support to engage and retainthe remaining filaments, and finally means to grip and draw the fleeceformed by the intermeshing of the filaments engaged by said tubularelement and said net-like support.

The invent-ion will be more fully understood from the preferredembodiment to be now described, with reference to the accompanyingdrawings wherein:

FIG. 1 is a diagrammatic end view of this embodiment; and

FIG. 2 is a diagrammatic plan view thereof.

With reference to the drawing, numeral 10 indicates the filaments, shownin dotted lines. The filaments are engaged and advanced by a drum 11,which rotates in a semi-cylindrical shell 12 and mounted on a base 13.After having described an angle of about around said cylinder, thefilaments are separated therefrom by a stationary wedge or knife 14 atthe outlet portion 21 of the shell 12 which directs them into a fixedconduit 15;

The fixed conduit 15 is tapered as can be seen in FIG. 2, so that thefilaments advancing therein under the action of the stream of airproduced by the drum 11 in its rotation converge toward one another. Atthe outlet end of the fixed conduit 15 there is mounted a short pivotalconduit 16 in the shape of a parallelepiped sleeve oscillatable around apin 17 in an inclined plane (see FIG. 2),, in such a way as to describethe same angle to the right and to the left of the axis 18 of the fleece19. The means for producing the oscillation of the sleeve 16 is notillustrated but may be any conventional Well-known means in the art.

The filaments 10 that pass from the conduit 15 to the sleeve 16 are thusprojected from the latter by the stream of air generated by the drum 11in varying directions depending on the instantaneous angular position ofthe sleeve 16. In the path of the filaments issuing from sleeve 16 thereis interposed a tubular rod 20 normal to the axis 18. Beneath rod 20there are arranged two nets or screens 21 placed close to each other insuch a way as to leave a slit 22 therebetween.

Part of the filaments thus projected from sleeve 16 by the stream of airgenerated by the drum 11 are deposited directly on the nets or screens21; and, since the sleeve is oscillating transversely with respect tothe average direction of travel of the filaments, this causes thefilaments to assume on the nets or screens a substantially transverseconfiguration. Some of the filaments impinge rod 20 and they ridethereon. The air leaving the sleeve -16 meshes the filaments depositedon the nets or screens and those filaments which straddle the rod 20,the latter nevertheless being long enough so that they have at least apart thereof meshing with the filaments deposited on the nets or screens21; and other parts thereof projecting through the slit or gap 22. Allthose filaments which straddle the bar 20 or are deposited on thescreens 21 have a comparatively great length, for instance 50 to 100 cm.average, and constitute a fleece 19, which, once introduced into theslit 22, is gripped by a take-up device which may conveniently comprisean endless conveyor belt 23 and a feed roller 24, pressed against thedrive roller 25 supporting the belt 23 at one end thereof.

In operation, the drum 11 is rotated by conventional means, such as amotor and transmission (not shown) in the direction indicated by thearrow in FIG. 1 and at very high speed so that its peripheral speed willbe in the order of 4000 meters per minute. Since its cylindrical surfacerotates in close proximity to the semi-cylindrical shell 12, the skin orsurface friction effect will generate a substantial stream of air toflow in the interspace between the periphery of the drum 11 and theshell 12. This stream is deviated by the stationary wedge 14 and flowsinto the tapered conduit, whence, due tothe convergence of the sidewalls of this conduit, it is emitted at high speed through the pivotedconduit 16 to impinge onto the bar 20 and the upper and lower screens21.

The filamentary material 10, which enters the interspace between thedrum 11 and the inlet portion 26 of the shell 12 will be carried alongwith said stream; and the individual filaments, which, as above stated,are pretty long (such as from 50 to 100 centimeters), will beparallelized by the action of the drum, and will be projected from thepivoting conduit 16 onto the rod 20 and the screens 21. Such filamentsare essentially oriented in the direction of the stream, and willimpinge on said screens more or less perpendicular thereto.

It is evident that such light weight and liable filaments will tend tolie on any surface on which they have impinged, and that they will beoriented randomly on the rod 20 and the screens 21, being pressedthereon by the stream of air. Such randomly arranged filaments willinclude a number of filaments which are nearly parallel to the rod 20, anumber of which are nearly perpendicular thereto, which will bedeposited astraddle the member 20, while the remaining filaments willform diiferent angles with said member 20, and some of these latterfilaments will lie diagonally astraddle thereof.

After a short time of operation, there will be formed on the rod 20 andscreens 21 a soft layer or felt of randomly oriented filaments, in whichthe filaments superimpose and intercross with one another in mutuallyentangled relationship. This soft layer will extend both above and belowthe rod 20, and its lower end will span the slit 22. The width of thislayer, which is a function of the angle of swing of the conduit 16 aboutits pivot 17, will determine the width of the fleece which is to beproduced.

After a suflicient thickness of layer has been laid down, the operatormanually feeds the lower end of the layer of filaments through the slit22 and into the bite between the roll 24 and the conveyor 23 at the roll25. The conveyor 23 thereupon will start drawing the layer through theslit 22. The drawing of the thus formed web is performed at a relativelylow linear speed, such as 0.2 to 1.5 meters per minute; and the rate atwhich the filamentary material is fed in the apparatus and projected bythe air stream onto the rod and the screens is so adjusted that asubstantial amount of the filaments will be present at any given time onthe rod 20 and screens 21 so that the layer of intercrossing andentangled filaments will be continuously formed, and will be coherentenough to be pulled through the slit 22 by the conveyor 23 in the bitebetween the roll 24 and the conveyor. Thus, the fleece is continuouslyformed, the filaments, which are oriented longitudinally in-thedirection 18 of movement of the conveyor being caught and drawn by theirleading end portions onto the conveyor, while the transversely orientedfilaments are'carried on with these longitudinally oriented filaments,since they are entangled therewith and located between a number ofoverlying and underlying longitudinal filaments. Of course, properoperation of the apparatus requires that the feeding of the filamentsonto the rod 20 and screens 21 be adjusted so that a substantial layerof randomly oriented filaments will always lie and be formed on thescreens to insure drawing of the Web of filaments through the slit 22.

It has been found that the presence of the rod 20 causes thosefilaments, which are not deposited directly on the nets or screens 21but settle on the rod instead, to remain for a certain length'of time onthe rod and to be subjected to the action of the stream of air issuingfrom sleeve 16. The stream of air tends to comb these filaments andcause them to assume a direction substantially parallel to the averagedirection of travel of the filaments, that is, longitudinal with respectto the direction of axis 18. Instead the filaments that deposit on netsor screens 21 have prevailingly transverse direction owing to thepivotal movement of the sleeve 16, and come to bind in sideways thefilaments placed longitudinally. As a consequence, the fila-' ments arepartly arranged in transverse direction and partly longitudinally, andtransversely extending filament s mesh with one another, and a certainnumber of longitudinal filaments protrude through the slit or gap 22 toa point where they become engaged between the belt 23 and the roller 24of the take-up device. These filaments are drawn by the traveling beltthrough the gap 22 and are advanced in the direction of the travel ofbelt 23, and the longitudinal filaments carry with them the transverselyarranged filaments meshing with them to form a continuous mat or web 19which is drawn through slit 22 and carried forward by belt 23. Thefleece transported in the said manner by the roller 24 and belt 23, isthen conveniently glued, and dried, to bond the various filaments, inthe usual manner which need not be described herein.

The amplitude of the angle described by the sleeve 16 is related to thewidth of the fleece to be obtained, and is so calculated. It is evident,in particular from corn sideration of FIG. 2, that the filaments will bespread on the screens 21 over a width which is proportional to theamplitude of swing of the sleeve or conduit 16 about its pivot 17, andto the distance between said pivot and the surfaces on which thefilaments are caused to impinge. As shown in FIG. 2, the width of theproduced fleece 19 corresponds to the width of thepart of the screens 21on which the filaments have been spread by the swinging conduit 16. Thefrequency of the pendular movement of said sleeve is preferably of from40 to oscillations (complete oscillations) per minute; it determines thedistribution of the filaments over the area described by the movement ofthe sleeve 16. The peripheral speed of the rollers 24, 25 determines (atequal peripheral speed of the cylinder 11) the weight of the fleece persurface unit (unit area). So if the cylinder 11 has a peripheral speedof the order of magnitude of 4000 meters per min ute, the rollers 24, 25may have a speed of 0.2 to 1.5 meters per minute. In any case the latteris always comparatively low. The position of the tubular rod 20 mayvary; It may be in contact with the nets orscree'ns 21, or havetherefrom an even considerable distance for instance up to 400 mm. Also,it may be located as indicated in FIG. 1, on the extension of the middleplane of sleeve 16 or it may be above or below said plane, forinstance,by up to a distance of 200 mm. above or below Thesedisplacements of position of the rod 20 determine the ratio between thenumber of filaments which become arranged along the axis of the fleece,and the number of the filaments which become arranged transversely,whereby they determine the ratio between the longitudinal strength andthe transverse strength of said fleece,'under otherwise equalconditions.

An embodiment of the invention has been described but not y Way oflimitation; however it is apparent that the invention can be embodied inmany adaptations and modifications by those skilled in the art.

We claim:

1. A process for manufacturing a fleece from glass or like mineralfibers comprising,

(a) advancing a plurality of filaments along a portion of a cylindricalsurface by the action of a stream of air,

(b) separating said filaments from said surface after a predeterminedadvance therealong,

(c) continuing to advance said filaments after the separation thereoffrom said surface, while simultaneously drawing them closer to oneanother,

(:1) then projecting the filaments in a periodically variable directiononto a support so that the filaments become arranged in mutuallycrossing directions and mutually intermesh, and

(e) continuously Withdrawing the filaments as a fleece from saidsupport.

2. A process as defined in claim 1 wherein in projecting the filaments,they are subdivided into two groups, the filaments of one group beingprojected onto said support in a direction longitudinal of the axis ofthe fleece to be obtained, and the filaments of the other group beingprojected onto said support in zigzag fashion with respect to said axis.

3. Apparatus for manufacturing fleece from mineral fibers of glass orthe like comprising,

(a) means for producing a plurality of parallel glass filaments,

(b) a rotating drum for engaging and guiding said filaments along itsperipheral surface as it rotates,

(c) a shell radially spaced from and enveloping a portion of said drum,to define therewith a narrow space through which the filaments travel,

(d) said drum being operative upon rotation thereof to generate a streamof air,

(e) a fixed guide member for separating said filaments from said drumafter passage of said filaments through said space,

(f) a fixed conduit communicating at one end with said space adjacentsaid guide to receive said stream of air and the filaments separatedfrom said drum,

and having a tapering cross section thereby to draw said filamentscloser to one another as they advance toward the opposite end of saidconduit,

(g) a movable conduit communicating at one end with said opposite end ofsaid fixed conduit and having an outlet opening at its other end, saidmovable conduit being oscillatable to discharge said filaments invariable directions,

(h) a net-like stationary support positioned in front of said movableconduit to receive some of the filaments discharged from said movableconduit,

(i) an element positioned between said movable conduit and said supportto engage others of said filaments, and

(j) take-up means adjacent said support operative for gripping anddrawing otl from said element and from said support said filaments inintermeshed relation whereby the form the fleece.

4. Apparatus as defined in claim 3 wherein said stationary supportcomprises two screens positioned side by side but separated by a slitthrough which said fleece is adapted to be drawn by said take-up means.

5. Apparatus as defined in claim 3 wherein said takeup means comprisesat least one rotatable take-up feed roller and having a peripherialspeed corresponding to the weight per unit area desired in the fleece.

6. Apparatus as claimed in claim 3 wherein said movable conduit isoperative to cause a corresponding increase or decrease in the width ofthe fleece produced on said support upon an increase or decrease,respectively, in the total pivotal displacement in operation of saidmovable conduit.

References Cited in the file of this patent UNITED STATES PATENTS2,931,421 Schuller Apr. 5, 1960 2,976,580 Riedel Mar. 28, 1961 FOREIGNPATENTS 159,324 Australia Oct. 14, 1954

3. APPARATUS FOR MANUFACTURING FLEECE FROM MINERAL FIBERS OF GLASS ORTHE LIKE COMPRISING, (A) MEANS FOR PRODUCING A PLURALITY OF PARALLELGLASS FILAMENTS, (B) A ROTATING DRUM FOR ENGAGING AND GUIDING SAIDFILAMENTS ALONG ITS PERIPHERAL SURFACE AS IT ROTATES, (C) A SHELLRADIALLY SPACED FROM AND ENVELOPING A PORTION OF SAID DRUM, TO DEFINETHEREWITH A NARROW SPACE THROUGH WHICH THE FILAMENTS TRAVEL, (D) SAIDDRUM BEING OPERATIVE UPON ROTATION THEREOF TO GENERATE A STREAM OF AIR,(E) A FIXED GUIDE MEMBER FOR SEPARATING SAID FILAMENTS FROM SAID DRUMAFTER PASSAGE OF SAID FILAMENTS THROUGH SAID SPACE, (F) A FIXED CONDUITCOMMUNICATING AT ONE END WITH SAID SPACE ADJACENT SAID GUIDE TO RECEIVESAID STREAM OF AIR AND THE FILAMENTS SEPARATED FROM SAID DRUM, ANDHAVING A TAPERING CROSS SECTION THEREBY TO DRAW SAID FILAMENTS CLOSER TOONE ANOTHER AS THEY ADVANCE TOWARD THE OPPOSITE END OF SAID CONDUIT, (G)A MOVABLE CONDUIT COMMUNICATING AT ONE END WITH SAID OPPOSITE END OFSAID FIXED CONDUIT AND HAVING AN OUTLET OPENING AT ITS OTHER END, SAIDMOVABLE CONDUIT BEING OSCILLATABLE TO DISCHARGE SAID FILAMENTS INVARIABLE DIRECTIONS, (H) A NET-LIKE STATIONARY SUPPORT POSITIONED INFRONT OF SAID MOVABLE CONDUIT TO RECEIVE SOME OF THE FILAMENTSDISCHARGED FROM SAID MOVABLE CONDUIT, (I) AN ELEMENT POSITIONED BETWEENSAID MOVABLE CONDUIT AND SAID SUPPORT TO ENGAGE OTHERS OF SAIDFILAMENTS, AND (J) TAKE-UP MEANS ADJACENT SAID SUPPORT OPERATIVE FORGRIPPING AND DRAWING OFF FROM SAID ELEMENT AND FROM SAID SUPPORT SAIDFILAMENTS IN INTERMESHED RELATION WHEREBY THE FORM THE FLEECE.